Transcript File

CELLULAR
RESPIRATION
MAKING LINKS
FORMULA OF PHOTOSYNTHESIS:
Energy+CO2+H2O+Enzymes→ Glucose + O2
FORMULA OF RESPIRATION
Glucose+O2 +Enzymes→ Energy+CO2+H2O
FORMULA OF COMBUSTION
Fuel+O2 →Energy+CO2
USES OF ENERGY
 Growth
 Movement
 Cell division
 Maintaining body temperature
 Active transport
Adenosine Triphosphate (ATP)
 Adenosine Diphosphate (ADP) + P + Energy = ATP
Video ATP production
Structure and function of a
mitochondrion (The site of Aerobic
respiration)
 Draw, label and annotate a diagram of a mitochondrion (pg
184)
AEROBIC RESPIRATION
(PROCESS)
1. GLYCOLYSIS
Glucose (6C) is split into two pyruvic acid
(3C)
In the cytosol of cytoplasm.
Redraw fig 2.3.4 pg 185
ATP released + energised H carried by coenzyme
2. KREB’S CYCLE
In mitochondria
Energised H (carried by co-enzyme) and
CO2 are released
3. OXIDATIVE PHOSPHORYLATION
In the mitochondria
Hydrogen is carried from co-enzyme to coenzyme, releasing energy that is used to
create ATP molecules.
The H eventually joins with O to form
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ACTIVITY TIME
Activity 2.3.1 pg 186 No 2 &3
Activity 2.3.4 pg 189
ANAEROBIC RESPIRATION
(ABSENCE OF OXYGEN)
Starts with glycolysis (same as in aerobic
respiration)
IN PLANTS AND SOME MICROORGANISMS:
The pyruvic acid is converted into ethanol
and CO2.
IN ANIMALS:
Pyruvic acid is converted into lactic acid.
ANAEROBIC RESPIRATION IN
HUMANS
Normally aerobic respiration
When too much energy needed and low
supply of O2, anaerobic respiration occurs
forming lactic acid.
Build up of lactic acid → Cramps
As you breathe O2 converts the lactic acid
into CO2, water and glucose.
Anaerobic respiration in microorganisms
Yeast (and plants):
Glucose→ pyruvic acid → ethanol and CO2
 Yeast → bread and wine/beer
Some bacteria (and animals):
Glucose→ pyruvic acid → lactic acid
 Bacteria → cheese and yoghurt
Anaerobic vs aerobic respiration
SIMILARITIES:
 Both need glucose and do glycolysis
 CO2 released
 ATP formed
Differences between aerobic and
anaerobic respiration
AEROBIC RESPIRATION
ANAEROBIC RESPIRATION
Needs O2
No O2 used
36 ATP produced (net)
2 ATP produced (net)
Produces CO2 and water
Produces alcohol and CO2 (in
plants/micro-organisms) OR
Lactic acid (animals)
Act 2.3.8 pg 198
PRACTICAL WORK (Bring
textbook)
Test for CO2
 Clear lime water turns milky in the presence of CO2
ACT 2.3.3 pg 188.
ACT 2.3.9 pg 199
Aim: To demonstrate that oxygen
is used during respiration
 Apparatus:
 Two vials
 2 stoppers
 2 gauze sacs with lining
 Germinating seeds
 Boiled seeds
 Methylene blue solution
 Pipette
 1. Use pipette to place half of methylene blue solution into each of the
large vials.
 2. Place some germinating seeds in the damp gauze.
 Pull the edges of the gauze to enclose seeds in a sac.
 Tie the loose ends of the gauze leaving a long end free.
 Suspend the sac with germinating seeds over the methylene blue
solution in vial 1.
 Leave the loose end out of the vial.
 Place the lid on vial 1.
 Trim off the excess gauze.
 3. Place some of the dead seeds in vial 2 in the same way as was
done in vial 1.
 [Precautions: the seeds were boiled for a few minutes in water to
kill it and then
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soaked in formalin to prevent fermentation]
 4. Place both sets of apparatus in a dark place to prevent
photosynthesis.
 5. Observe the changes in the contents of the vials at intervals of 10
minutes.
 NOTE:
-Methylene blue solution is an indicator:
When oxygen is present = blue
When oxygen is absent = colourless
 Observations:
Vial
1
2
State of
seeds:
living/dead
Colour of
methylene blue
solution at the
beginning of
the experiment
Colour of
methylene
blue solution
at the end of
the experiment
Oxygen:
present/absen
t
Vial
State of
seeds:
living/dead
Colour of
methylene blue
solution at the
end of the
experiment
Colourless
Oxygen:
present/absen
t
Living
Colour of
methylene blue
solution at the
beginning of
the experiment
Blue
1
2
Dead
Blue
Blue
Present
Absent
Observations:Discussion:
In vial 1, the methylene blue solution becomes colourless.
In vial 2, the methylene blue solution remained the same (blue).
Conclusion:
•Since methylene blue solution becomes colourless only in the absence
of oxygen, oxygen must have been absorbed /removed from vial 1.
•Since the only difference between vial 1 and 2 is that in vial 1 we have
germinating seeds while in vial 2 we have dead seeds, the germinating
seeds must have absorbed the oxygen.
•Germinating seeds undergo rapid cellular respiration in order to produce
large amounts of energy which is necessary to initiate and maintain
growth.
•We conclude, therefore, that it is the process of cellular respiration
which has absorbed the oxygen i.e. oxygen is necessary for cellular
respiration.
Aim: To demonstrate that oxygen
is used during respiration
 Apparatus: 2 x test tubes, soda lime, perforated partition to
fit in test tubes, one-hole stoppers, right angle glass tubes,
beakers, coloured water, and matches.
 Method:
 Experimental Procedure:
 Test tube with soda lime - soda lime will remove CO2 from the air.
 Place a small animal, e.g., a beetle, in the test tube with a perforated
partition between it and the soda lime.
 Seal the test tube with a one-hole stopper with a right angle glass tube
leading into a beaker of coloured water.
 Keep the temperature constant at room temperature, 20°C thermostatically regulated heating system.
 Why the temperature is kept constant?
Gases expand when heated and contract when cooled. Volume
changes due to temperature changes would upset the true results
of the experiment. Any volume change must only be due to the
animal.
 Precaution: use a sterilising solution to kill any micro-organisms on
the inside of the glassware - so that the animal is the only live
organism and it alone is responsible for the consumption of O2.
 Control Procedure:
Same set-up but there is no animal in the test tube.
 When the experiment is completed, test the air in each test tube with
a burning match. Observe.
 Observations:
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 Discussion:
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 Conclusion:
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Observations:
Control: no change in the level of water in the glass tube - same level as the
water in the beaker.
Experiment: water has risen up the tube towards the test tube containing the
animal. The air remaining in the test tube does not allow the match to burn in
it.
Discussion:
CO2 is produced and excreted into the air as fast as O2 is used up and
extracted from the air. The soda lime absorbs the CO2 from the air. The mass
of the air reduces because it is losing O2 to the animal. This reduces the air
pressure in the test tube. There is now a pressure difference - higher air
pressure outside.
The liquid in the beaker is pushed up the tube towards the animal. This keeps
the air pressure in the test tube constant at atmospheric pressure. The air
remaining in the test tube does not allow the match to burn in it. Therefore the
air has lost oxygen.
Conclusion:
Oxygen was only removed from the air when the live animal was present.
The animal is responsible for the loss of oxygen from the air - therefore the
animal respired aerobically.
 WORKSHEET 4
 Aim: To determine if carbon dioxide is given off during respiration
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Apparatus:
Two test tubes
20 bean seeds
Lime water or bromothymol blue solution
Petroleum jelly
Two rubber stoppers
Foam rubber
Bleach or formalin
Method:
Soak 10 beans in water for 24 hours so that they absorb water and germinate.
Boil 10 bean seeds to kill them. Let them cool down. Rinse well in bleach.
Pour 5 ml of lime water/ bromothymol blue solution into each test tube. Both these
indicators change colour in the presence of carbon dioxide.
Place a piece of foam rubber into each test tube so that it is just above the indicator
solution, but not touching it.
Place the live seeds in one test tube so that they rest on the foam rubber. Seal the test
tube with a rubber stopper covered in petroleum jelly.
Place the dead seeds in one test tube so that they rest on the foam rubber. Seal the test
tube with a rubber stopper covered in petroleum jelly. This is the control test tube.
Leave the test tubes overnight.
Observe changes in the indicator solution the next day.
Observations
•Complete the table
Colour of the indicator solution
at the start of the experiment
Colour of the indicator solution
at the end of the experiment
Discussion
What did you observe in the two test tubes? Explain your answer.
_______________________________________________________________
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Why did you boil some of the seeds and wash them in bleach?
_______________________________________________________________
Explain how your results could have been affected if you did not wash the seeds in
bleach.
_______________________________________________________________
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If I would use a plant in this investigation, the experiment should be placed in a dark
cupboard. Why?
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Colour of the indicator solution
at the start of the experiment
Clear lime water
OR
Bromothymol blue: blue
Colour of the indicator solution
at the end of the experiment
Milky lime water
OR
Bromothymol blue: yellow
Discussion
The lime water/bromothymol blue solution change colour when carbon dioxide
is present. The clear lime water turns milky and the bromothymol blue
solution turns yellow.
Dead seeds do not respire. The bleach will prevent the growth of bacteria
which can also produce CO2.
CO2 could not have been produced – the lime water will stay clear.
In normal light photosynthesis is faster than respiration. Therefore all the CO2
produced by respiration will be used for photosynthesis - the plant will not
release CO2. Photosynthesis has to be stopped without damaging the plant so keep the plant in darkness.
Conclusion
The release of carbon dioxide by the living seeds indicates that respiration
is taking place.